From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934633Ab1JaTIR (ORCPT ); Mon, 31 Oct 2011 15:08:17 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:44251 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934504Ab1JaTF7 (ORCPT ); Mon, 31 Oct 2011 15:05:59 -0400 From: Tejun Heo To: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Cc: arnd@arndb.de, oleg@redhat.com, matthltc@us.ibm.com, Tejun Heo Subject: [PATCH 10/17] freezer: test freezable conditions while holding freezer_lock Date: Mon, 31 Oct 2011 12:05:21 -0700 Message-Id: <1320087928-32307-11-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.3.1 In-Reply-To: <1320087928-32307-1-git-send-email-tj@kernel.org> References: <1320087928-32307-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org try_to_freeze_tasks() and thaw_processes() use freezable() and frozen() as preliminary tests before initiating operations on a task. These are done without any synchronization and hinder with synchronization cleanup without any real performance benefits. In try_to_freeze_tasks(), open code self test and move PF_NOFREEZE and frozen() tests inside freezer_lock in freeze_task(). thaw_processes() can simply drop freezable() test as frozen() test in __thaw_task() is enough. Note: This used to be a part of larger patch to fix set_freezable() race. Separated out to satisfy ordering among dependent fixes. Signed-off-by: Tejun Heo Cc: Oleg Nesterov --- kernel/freezer.c | 3 ++- kernel/power/process.c | 16 +--------------- 2 files changed, 3 insertions(+), 16 deletions(-) diff --git a/kernel/freezer.c b/kernel/freezer.c index 05afd68..5c911c0 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -109,7 +109,8 @@ bool freeze_task(struct task_struct *p, bool sig_only) spin_lock_irqsave(&freezer_lock, flags); - if (sig_only && !should_send_signal(p)) + if ((p->flags & PF_NOFREEZE) || + (sig_only && !should_send_signal(p))) goto out_unlock; if (frozen(p)) diff --git a/kernel/power/process.c b/kernel/power/process.c index e6e2739..e59676f 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -22,14 +22,6 @@ */ #define TIMEOUT (20 * HZ) -static inline int freezable(struct task_struct * p) -{ - if ((p == current) || - (p->flags & PF_NOFREEZE)) - return 0; - return 1; -} - static int try_to_freeze_tasks(bool sig_only) { struct task_struct *g, *p; @@ -52,10 +44,7 @@ static int try_to_freeze_tasks(bool sig_only) todo = 0; read_lock(&tasklist_lock); do_each_thread(g, p) { - if (frozen(p) || !freezable(p)) - continue; - - if (!freeze_task(p, sig_only)) + if (p == current || !freeze_task(p, sig_only)) continue; /* @@ -181,9 +170,6 @@ void thaw_processes(void) read_lock(&tasklist_lock); do_each_thread(g, p) { - if (!freezable(p)) - continue; - if (cgroup_freezing_or_frozen(p)) continue; -- 1.7.3.1